Abstract: A process for preparing syndiotactic vinyl aromatic polymers comprising contacting at least one polymerizable vinyl aromatic monomer under polymerization conditions with a catalyst comprising a compound corresponding to the formula:L.sub.m MX.sub.n.sup.+ RA.sup.-,wherein:L is a delocalized .PI.-bonding group containing up to 50 nonhydrogen atoms;m is 0 or 1;M is a metal of Group 4 of the Periodic Table;X each occurrence is an inert, anionic ligand containing up to 20 nonhydrogen atoms;n is an integer greater than or equal to 1 and the sum of m and n is one less than the valence of M; andRA.sup.- is .sup.- RB(C.sub.6 F.sub.5).sub.3, where R is hydride, hydrocarbyl, silyl, a combination thereof or a substituted derivative thereof having up to 20 nonhydrogen atoms. Also included is a process for preparing the catalyst.

Abstract: A catalyst composition for preparation of polymers of vinyl aromatic monomers having high syndiotacticity comprising a cationic coordination complex and a metal hydrocarbyl.

Abstract: Syndiotactic polymers of vinyl aromatic monomers are prepared by conducting the polymerization in the presence of a catalytic amount of the reaction product of polymethylaluminoxane and a cyclopentadienyl/titanium complex.

Abstract: Syndiotactic homopolymers of an arylcyclobutene functional monomer and syndiotactic copolymers of an arylcyclobutene functional monomer and a vinylaromatic monomer are prepared by conducting the polymerization in the presence of a catalytic amount of a suitable coordination catalyst such as the reaction product of polymethylaluminoxane and a transition metal compound.

Abstract: A process for preparing syndiotactic vinyl aromatic polymers comprising contacting one or more aromatic monomers under polymerization conditions with a catalyst corresponding to the formula:[Cp.sub.m MX.sub.n X'.sub.p ].sup.+ A.sup.-wherein:Cp is a single .eta..sup.5 -cyclopentadienyl or .eta..sup.5 -substituted cyclopentadienyl group;M is a metal of Group 3, 4, 5, 6, 8, 9, 10 or the Lanthanide Series of the Periodic Table;X each occurrence is an inert anionic ligand, with the proviso that at least one X is R;X' is an inert, neutral, donor ligand;R is hydride hydrocarbyl, silyl, a combination thereof or a substituted derivative thereof having up to 20 carbon, silicon or carbon and silicon atoms;m and p are independently 0 or 1;n is an integer greater than or equal to 1;the sum of m and n is equal to the valence of M; andA.sup.- is a noncoordinating, compatible anion of a Bronsted acid salt.

Abstract: Syndiotactic polymers of vinyl aromatic monomers are prepared by conducting the polymerization in the presence of a catalytic amount of the reaction product of polymethylaluminoxane and a cyclopentadienyl/titanium complex.

Abstract: An improved process for the preparation of aluminoxanes comprising contacting an aluminoxane precursor such as a hydrocarbyl substituted aluminum compound with a porous organic or inorganic aqueous imbiber material containing water sorbed or imbibed therein.

Abstract: Polymers of vinyl aromatic monomers having a high degree of syndiotacticity are prepared by contacting with a catalyst comprising a cyclopentadienyl zirconium (IV) complex and polymethylaluminoxane under polymerization conditions.

Abstract: Polymers of vinyl aromatic monomers having a high degree of syndiotacticity are prepared by contacting with a catalyst comprising a zirconium (IV) complex and polymethylaluminoxane under polymerization conditions.

Abstract: The specification discloses pentaalkylcyclopentadienyl actinide complexes and their use as catalysts for polymerizing lower molecular weight alkenes.

Abstract: Catalyst compositions are disclosed which are a combination of a supported titanium compound such as titanium tetraisopropoxide supported on magnesium dichloride and at least one other supported metallic catalyst such as dicyclopentadienyl zirconium dichloride supported on alumina and a cocatalyst such as aluminoxane. These catalysts are useful in the polymerization of .alpha.-olefins.